New research indicates that dopamine does not play a direct causal role in experiencing the effects of treatment, such as establishing positive treatment expectations and placebo-induced pain relief in healthy individuals. This information comes from a study published on September 24 in the open-access journal PLOS Biology by Ulrike Bingel and her team from University Hospital Essen, Germany.
Recent research suggests that dopamine may not directly influence the effects experienced during treatment, particularly in relation to establishing positive treatment expectations and placebo-related pain relief among healthy subjects, according to a study released on September 24 in the open-access journal PLOS Biology by Ulrike Bingel and colleagues from the University Hospital Essen in Germany.
There has been a belief that dopamine, which is associated with reward and learning, contributes to placebo effects. However, the specific role of this brain chemical in creating and maintaining those effects is not fully understood. To address this gap in knowledge, Bingel and her colleagues investigated the role of dopamine in forming positive treatment expectations and measuring the intensity and duration of their effects on pain. They conducted a double-blind, randomized, placebo-controlled trial that included 168 healthy volunteers and utilized a well-established placebo pain relief method, along with two different medications: the dopamine-blocking drug sulpiride, the dopamine precursor L-dopa, and an inactive control pill with no medication.
The medications effectively modified dopamine levels during the learning phase. Contrary to initial predictions, the medications did not influence the development of positive treatment expectations or placebo pain relief, which were evaluated a day later. Notably, the effects of placebo analgesia had diminished by the eighth day following conditioning. The findings strongly argue against a direct impact of dopamine on the creation and sustenance of placebo effects.
The study indicates that while dopamine is not essential for establishing placebo-induced pain relief, aspects of reward processing related to active engagement and motivation may still interact with pain perception. Additionally, these results enhance the understanding of the brain mechanisms involved in placebo analgesia, highlighting the complex relationships between cognitive factors, neurochemistry, and treatment outcomes.
The researchers emphasize the importance of further investigating the neurochemical processes associated with placebo analgesia to maximize these effects for better treatment results. Future studies focused on dopamine’s role in modifying treatment responses in pain should take into account the complex nature of how dopamine transmission interacts with pain and its management.
The authors conclude, “Our research aims to uncover the mechanisms behind placebo effects to improve the effectiveness of active medical treatments. The findings from our study help redirect the focus toward new treatment targets to achieve this goal.”
